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High Altitude Sickness

Physical fitness while trekking in Nepal:

One should be mentally and physically fit for trekking 5 to 7 hours each day. Normally the trek may begin at lower altitude gaining relatively elevation each day. We recommend those suffering from heart and lungs problems not to attempt any strenuous or high altitude treks. Of course, consultation with your doctor regarding medical and physical fitness before trekking is always advisable.

The three golden rules of altitude bear repeating.

1.    If you feel unwell at altitude, it is altitude sickness until proven otherwise.
2.    Never go higher if you have symptoms of AMS.
3.    If you are getting worse (or have HACE or HAPE), go down at once.

Acute Mountain Sickness (AMS)

AMS happens when you are not acclimatized. AMS has been likened to a bad hangover. The symptoms are very general or non specific. For some reason, many people do not like to believe they have altitude sickness – they blame everything else – hence golden rule number one. (If you feel unwell at altitude, it is altitude sickness until proven otherwise)
Summary of different types of Altitude illness:

Different types of altitude Illness – symptoms/ signs after recent ascent
Modified from Lake Louise on definition of Altitude Illness
AMS    Headache plus one of the following
•    Loss of appetite, nausea or vomiting
•    Fatigue or weakness
•    Dizziness or lightheadedness
•    Difficulty sleeping


Two of the following
•    AMS
•    Confusion, change in behaviour
•    Loss of coordination/ Cannot walk strait line


Two of the following

•    Extreme tiredness or drowsiness
•    Breathless at rest
•    Fast shallow breathing
•    Cough with pink frothy sputum
•    Gurgling or rattling breaths
•    Chest tightness, fullness or congestion
•    Blue or grey lips or fingernails

How can I tell if a headache is due to altitude?

A common question is how to tell if a headache is due to altitude (refer to golden rule number one). Altitude headaches result from swelling of the brain. They tend to be at the front of the head (but can be elsewhere), worse when bending over, and quite painfull and persistent. Frequently there are other symptoms of AMS. You can try this simple test. Dehydration is a common cause of headache at altitude so drink one litre of fluid and take some analgesic e.g. ibuprofen. If your headache goes away quickly and completely, and you have no other symptoms of AMS, it is very unlikely to have been due to AMS.
High Altitude Cerebral Edema – HACE

HACE means, the brain is really swollen from lack of oxygen and so it does not work. This means the sufferer is often not aware of how sick they are. A good test for lack of coordination/brain function is to draw a straight line on the ground and ask the sufferer to walk along it heel toe, placing one foot immediately in front of the other. If they struggle to stay on the line or fall off, they should be presumed to have HACE.

High Altitude Pulmonary Edema – HAPE

HAPE may be present with or without symptoms of AMS or HACE. It is more frequent in young fit climbers or trekkers. HAPE usually occurs on the second night after ascent and caused breathing difficulties and coughing as outlined. Sufferers can deteriorate really rapidly in a short time.

HACE AND HAPE are rapidly fatal
Both these severe forms are usually first recognized or become worse at night. HACE and HAPE are dreadfully serious and can be fatal in a few hours if left untreated. Descent cannot wait until morning. Remember golden rule three. (If you are getting worse (or have HACE or HAPE), go down at once.) People with HACE and HAPE usually survive if they descend far enough – usually to the last elevation where they felt well – which is often two nights previously.


You do not have to descend if you only have a mild headache.

The foundation of treatment for Acute Mountain Sickness (AMS) is rest, fluids and mild painkillers e.g. paracetamole or ibuprofen. These medicines will not cover up worsening symptoms. Stay where you are. Remember golden rule two (Never go higher if you have symptoms of AMS.) People who get HACE or HAPE have usually ignored golden rule two. AMS will usually get better by itself, simply by resting at the altitude where you got sick. This usually takes 1-2 days but may take as long as 4 days. Descent will mean you get better faster.

Acetazolamide (Diamox) speeds the acclimatization to altitude. It is not a magic wand but it takes a process that might normally take 24-48 hours, speed up to about 12-24 hours. Acetazolamide may cause tingling in the fingers/palms/soles of the feet, and make you pass urine more frequently. Also fizzy drinks may taste strange.

Acetazolamide (Diamox) Treatment for AMS
250mg every 12 hours. Stop when symptoms go away
If acetazolamide is stopped, the acclimatization will slow down to your own intrinsic rate. There is no rebound effect. If you are acclimatized when you stop the tablet, you will stay acclimatized – you will not suddenly get worse when you stop.
If you are already taking acetazolamide for prevention, you can increase the dose to the treatment dose, Do not ascend higher.
If you are visiting high passes or Lhasa and wake during the first night with symptoms – take one 250mg acetazolamide (plus ibuprofen or paracetamole) to treat the headache, then continue with a 125-250mg every 12 hours for a few days until you feel better.
Dexamethasone is a potent steroid used to treat the brain swelling of AMS. It can completely remove the symptoms of AMS in a few hours. It only treats the symptom and does not speed up acclimatization. This medication ca be a trap – it can hide symptoms and give a false sense of security to those who want to continue traveling higher.
Dexamethazone Treatment for AMS
Two doses of 4mg, 6 hours apart. Never ascend until at least 12 hours after the last dose and only then if there are no symptoms of AMS
If you have symptoms of HACE OR HAPE
Remember golden rule three. There is no time to lose. Desced! Even 300 metres can make a huge difference. Even if it is the middle of the night, which it usually is, get the sufferer down. Be wary of companions who deny they are sick and refuse to descend. Change of personality is a sign or severe altitude sickness. Do not wait for a helicopter. Use whatever transport is available. If they cannot walk or stagger, they need to be carried sown by porter,  yak or horse. Severe altitude sickness requires urgent, experienced medical help and constant supervision. A Gamow bag (portable hyperbaric chamber) may buy some time.

Under no circumstances leave a sufferer unattended if they have any symptoms of altitude illness. They need to be watched in case they suddenly deteriorate.